Most RV dealers carry RV solar panel kits that you can install on the roof of your RV yourself. If you haven't priced these RV solar panel kits lately, you may be surprised at just how affordable they have become. They are also more efficient that earlier RV solar panel kits, which means you'll get more power charging for your buck when you invest in these kits.
The kits are easy to install; most do-it-yourselfers can complete the job in an afternoon, especially if they're only installing one or two RV solar panels. Be sure to ask your dealer how many panels you can link together in the system you choose, and what the maximum power output is for the panels you've chosen.